Metal forming



May 21, 1957 a. 00220 2,792,730

METAL FORMING Filed May 14, 1955 2 Sheets-Sheet 1 INVENTOR.

G/USEPPE Cazzo TMMW A H TTU/P VEKS G. cozzo METAL FORMING May 21, 1957 2Sheets-Sheet 2 INVENTOR. G/l/JEFPE Co zzc Filed May 14, 1953 jMMM 6rra/rwers METAL FGRMENG Application May 14, 1953, Serial No. 355,111 7Claims. (Cl. 80-56) This invention relates generally to the rolling ofmetal sheets or continuous strips, and is particularly directed to therolling of very wide metal sheets or strips to a relatively smalluniform or longitudinally tapered thickness, especially in rolling millsof the type usually referred to as four-high mills.

Conventional four-high mills include upper and lower worklng rollsbetween which the metal sheets or strips are fed and backing rolls inrolling contact with the relatively small diameter working rolls alonglines of contact which are substantially diametrically opposed to thelines of contact of the Working rolls with the metal sheet or strip. Theworking and backing rolls are mounted at the1r opposite ends in bearingblocks or chocks in the mill housings, and a roll pressure changing orscrew-down mechanism is operatively connected to the bearing blocks forchanging the pressure on the rolls and the thickness of the materialbeing rolled as it passes through the mill. It is known that the minimumthickness of the rolled sheet or strip, in the absence of theapplication of tension to the sheet or strip during rolling, is largelylimited by the diameter of the working rolls. That is, given a rollngmill with a screw-down mechanism capable of exertmg a certain maximumpressure on the rolls, the minimum thickness of the rolled sheet orstrip that is obtainable is smaller with relatively small diameterworking rolls and larger with relatively large diameter working rolls.Thus, very thin metal sheets or strips can be obtained with aconventional rolling mill by using small diameter working rolls.However, when it is desired to roll metal sheets or strips which areboth very thin and very wide and without resorting to the imposition oftension on the sheet or strip, a difficulty is encountered, for thesmall diameter working rolls required to produce a very thin rolledsheet do not have sufficient rigidity for the length thereof and tend tobow out from between the backing rolls to produce a rolled sheet orstrip which is of non-uniform thickness across the width thereof.

Accordingly, it is an object of the present invention to provide arolling mill of the described character capable of producing very thinand wide rolled sheets or strips which are of uniform thickness acrossthe width thereof.

Another object is to provide a rolling mill having the foregoingcharacteristics and arranged to produce longitudinally tapering sheetsor strips, wherein the roll pressure changing or screw-down mechanism issensitively responsive to control for obtaining a uniform taper.

In accordance with the present invention, a four-high rolling mill ofthe described character is provided with auxiliary backing means inrolling contact with one or" the working rolls to resist bowing of thelatter from between the main backing rolls, including a laterallyarranged series of auxiliary backing rolls. In addition, auxiliarybacking rolls also may be used in conjunction with the other workingroll.

Each of the auxiliary backing rolls of the laterally arranged seriesisindependently mounted and urged with a variable pressure against thecorresponding axial pornited States Patent tion of the related workingroll. A control system is provided for varying the contact pressure ofeach of the auxiliary backing rolls against the corresponding portion ofthe working roll and includes a laterally arranged series of gaugemechanisms responsive to the thickness of the rolled sheet or stripexiting from between the working rolls at the related lateral position,with each of the gauge mechanisms being operative to vary the contactpressure of a corresponding one of the auxiliary backing rolls tocorrect any bowing of the working roll and thereby avoid deviations inthe thickness of the rolled sheet or strip across the width thereof.

Further, in accordance with the present invention, the roll pressurechanging or screw-down mechanism includes screw shafts driven by asuitable reversible motor and engaging the roll carrying checks for theupper backing roll in the usual manner and an hydraulic motor orcylinder acting on each screw shaft to provide a substantial proportionof the pressure to be exerted by the roll pressure changing mechanism sothat the screw shafts can be driven by relatively small and responsiveelectric motors to provide the sensitivity of control required whenlongitudinally tapered sheets or strips are being rolled.

The above, and other objects, features and advantages of the inventionwill be apparent in the following description, when it is read inconnection with the accompanying drawings, forming a part hereof, andwherein:

Fig. l is a diagrammatic, vertical sectional view of a rolling millembodying the present invention;

Fig. 2 is a fragmentary, horizontal sectional view taken along the line2-2 of Fig. 1; and

Fig. 3 is a schematic, perspective view of the essential elementsincluded in the exemplary embodiment of the invention illustrated inFig. 1 some of the parts being omitted for clarity.

Referring to the drawings in detail, and initially to Fig. 1 thereof, afour-high rolling mill is there shown and generally identified by thereference numeral 10. The rolling mill 10 includes the usual housing 11which supports chocks (not shown) carrying upper and lower working rolls12' and 13, respectively, and upper and lower backing rolls 14 and 15,respectively. The working rolls 12 and 13 are disposed between thebacking rolls 14 and 15, and a roll pressure changing or screwdownmechanism, generally identified by the numeral 16, engages the rollcarrying chocks of the upper backing roll 14 to urge the upper backingroller downwardly with a variable pressure and thereby vary the contactpressure between the working rolls 12 and 13. The metal sheet or strip Sto be rolled is fed in the direction'of the arrow on Fig. 1 between theworking rolls 12 and 13 over guiding or conveying rollers 17, and themill is driven by a suitable constant speed motor (not shown) in theusual manner.

Assuming that there is a maximum force that can be exerted by thescrew-down mechanism 16, the minimum thickness to which the sheet S canbe rolled is determined in large measure by the diameters of the workingrolls 12 and 13. In any given rolling mill, and in the absence oftension applied to the sheet or strip during rolling, the minimumthickness achievable is reduced as the diameters of the working rollsare decreased. However, as the diameters of the working rolls aredecreased, the resistance to bending of such rolls is correspondinglyreduced so that, when a very wide sheet or strip is to be rolled to avery small thickness, the small diameter working rolls required for thatthickness are insufficiently rigid for the length thereof and theworking rolls 12 and 13 have a tendency to bow-out intermediate theirsupported? ends from between the backing rolls 14 and 15. Such bowing ofthe working rolls will produce a crowned rolled sheet or strip, that is,having a greater thickness at the center than at the opposite edgeportions thereof.

In accordance with the present invention a rolling mill of the describedcharacter is provided with mechanisms for obtaining roller sheets orstrips of equal thickness across the width thereof even though smalldiameter and long working rolls are employed in connection with therolling of very wide and thin sheets or strips. Such mechanisms mayinclude auxiliary backing rolls l5 and 19 arranged in front and in backof One of the working rolls, the upper working roll 12 in theillustrated embodiment (Fig. l). The auxiliary backing rolls 1% and 19are rotatably supported by fixed brackets 20 and 21, respectively, inrolling contact with the working roll 12 and act to prevent anydisplacement of the latter in the direction normal to the plane,indicated at 22, passing through the axes of rotation of the mainbacking rolls 14 and 15.

Since the working rolls 12 and 13 are preferably supported with theiraxes of rotation offset in one direction relative to the plane 22passing through the axes of the main backing rolls, it is apparent thatany deflection of the working rolls will be generally in the offsetdirection. Thus, in Fig. l the working rolls 12 and 13 have their axesdisposed in front of the vertical plane passing through the axes of themain backing rolls and any deflection of the lower working roll 13 mustoccur generally in the forward direction. Accordingly, a laterallyarranged series Of auxiliary backing rolls 23 are disposed in front ofthe lower working roll 13 and in rolling contact with related axialportions of the latter. Each of the auxiliary backing rolls 23 isindividually supported to bear rearwardly against the related portion ofthe lower working roll with a controllably variable pressure. By Way ofexample, in the illustrated embodiment of the invention, each of theauxiliary backing rolls 23 is rotatably carried by an individual yoke 24mounted on a ram 25 working in an hydraulic, or other pressure fluid,cylinder 26. The cylinders 26 are mounted on a common beam or housingpart 27 with their axes intersecting the axis of rotation of the lowerworking roll 13 and inclincd slightly from the horizontal in therearward and upward direction so that the auxiliary backing rolls 23 actagainst the related axial portions of the lower working roll 13 in adirection which substantially bisects the angle formed between thetangents to the roll 13 at the points of contact of the latter with thelower main backing roll 15 and with the upper working roll 12. Thus, theauxiliary backing rolls 23 act to wedge the related axial portions ofthe lower Working roll 13 between the rolls 12 and 15 and resist bowingof the lower working roll.

Further, in accordance with the present invention, the force exerted byeach of the laterally arranged series of auxiliary backing rolls 23 iscontrolled in response to the actual thickness of the portion of thesheet or strip rolled by the related axial portion of the lower workingroll, and more-particularly in response tothe deviation of that actualthickness from a predetermined or preselected thickness. Thus, as therolling mill 10 operates, a control arrangement, hereinafter describedin detail, measures or senses the thickness of the rolled sheet or stripat various locations across the width thereof and act in response to thedeviations of such measured thicknesses from a preselected thickness tovary the pressures in the several pressure fluid cylinders 26 andthereby either increase or decrease the force exerted by the auxiliarybacking rolls 23 acting against the axial portions of the lower workingroll corresponding to the portions of the sheet having thicknessdeviations so that the rolling pressure between such axial portions ofthe lower working roll and the upper working roll is either increased ordecreased, as the case may be, to correct such deviations from thepreselected thickness and provide a rolled sheet of uniform thicknessacross the width thereof.

A thickness gauge 28 is disposed at the exit side of the roll stand inalignment with each of the auxiliary back 4 ing rolls 23 to measure orsense the thickness of the related portion of the rolled strip S. Eachof the thickness gauges 28 may be of the kind known as the Electro-Limitor the Beta Ray Continuous gauges, such as are manufactured by the Pratt& Whitney Co., of Hartford, Qonnecticut. Each gauge 28 produces anelectrical signal which is related to the thickness of the sheet orstrip passing therethrough, and this signal is transmitted throughsuitable electrical connections to a corresponding meter 29 whichprovides a visual indication of the thickness. Preferably, the meters 2?are of the null type which can be adjusted to read zero if the actualthickness measured by the corresponding gauge 28 is correct. If theactual thickness measured by a gauge 2% deviates from the preselectedthickness, the corresponding meter 28 will show a plus or minus readingindicating that the actual thickness is greater or less than,respectively, the preselected thickness.

In order to control the pressure acting in the several pressure fluidcylinders 26 in response to the signals emanating from the gauges 23, asolenoid controlled valve 3t) (Fig. 3) is associated with each of thecylinders 26 and is actuated by such signals through a suitableelectrical connection 31 leading to the related gauge assembly. Thepressure fluid supply system includes a reservoir 32 for containing thepressure fluid and into which an outlet pipe 33 extends. A pump 34 isconnected to the outlet pipe to draw the pressure fluid from thereservoir, and the pump 34 is driven by a suitable motor 35. Thedischarge side of the pump 34 is connected to a supply manifold 36, anda by-pass line 37 leads back to the reservoir 32 from the supplymanifold through a suitable pressure relief valve 38 for regulating thepressure in the supply manifold. Each of the valves 36 is connected tothe supply manifold 36 through a pressure fluid supply pipe 39', and areturn pipe do also extends from each valve to a pressure fluid returnmanifold 41 extending back to the reservoir 32.. Finally, each of thevalves 30 is connected to the related cylinder 26 through a connectingpipe 42. Each of the valves 36 is arranged so that, depending upon thegauge signal furnished thereto, more or less of the pressure fluid ledto the valve through the supply pipe 39 is returned through the returnpipe 40 to adjust the pressure within the valve, and the connecting pipe4-2 communicates this adjusted pressure to the related cylinder 26.

Thus, the pressure in each of the cylinders 26 is adjusted in responseto the related gauge signal to vary the force exerted by thecorresponding auxiliary backing roll 23 against the lower working rollin a manner providing a rolled sheet or strip of uniform thicknessacross the width thereof.

While the above described arrangement is suitable for the production offlat sheets of uniform thickness across the width thereof, it may alsobe employed in connection with the production of sheets which arelongitudinally tapered. The rolling mill It can be adapted for theproduction of longitudinally tapered sheets by providing controlmechanism associated therewith for varying the pressure exerted by thescrew-down mechanism 16 as the sheet or strip is fed between the workingrolls. Such control mechanism may be of the kind disclosed in theco-pending application, Serial No. 265,992, filed January 11, 1952, nowPatent No. 2,655,823, and is generally indicated on Fig. 1 by thereference numeral 43. The gauges 28 can be related so that any deviationin transverse thickness will be corrected. The taper control mechanism43 controls a quick reversible motor 44 for operating the screw-downmechanism 16, the motor being driven at the desired speed in eachdirection for predetermined intervals to produce the required taper.However, mill deflection is present to a Variable degree so that merelyconstantly driving the screw-down motor 4 in either direction will notproduce a sheet which is.

uniformly tapered in the longitudinal direction. Therefore, thetapercontrol mechanism 43, as disclosed in t the above identified co-pendingapplication, preferably in cludes a taper corrective or compensatingarrangement for correcting the speed of the screw-down motor from itsbasic speed to a speed changing a predetermined amount at the times-orplaces required, as indicated by a gauge 45, so as to produce a sheet orstrip of uniform longitudinal taper.

It is apparent that the accuracy or uniformity of the longitudinal taperWill dependto a large extent upon the sensitivity or responsiveness ofthe screw-down motor 44 to the correcting impulses emanating from thegauge actuated compensating arrangement. Thus, it is desirable toemploya relatively small and sensitive electric motor for operation of thescrew-down mechanism 16. In order to permit the use of such a smallmotor, the screwdown mechanism 16, in accordance with the presentinvention, includes a worm 46 (Fig. 2) driven by the shaft of themotor4-4 and meshing with a worm gear 47 which is splined or keyed on avertical screw shaft 48 bearing downwardly at its lower end against thebearing blocks or chocks of the upper backing roll .14. The screw shaft48 extends threadably through a nut member 43 fixed in the housing 11.Thus, as the shaft 48 is rotated by the motor 44 through the mesh-inggears 46 and 47, the screw shaft is either raised or lowered, de-

pending upon the direction in which the motor is driven.

Since the screw shaft 48 impresses the load on the rolls of the mill, agreat reaction force acts axially on the screw shaft and results in arelatively great frictional resistance to turning of the screw shaft 48within the fixed nut member 49. Ordinarily, a relatively large motorwould be required to overcome this frictional resistance, however, inaccordance with the present invention, a piston 50 is provided on theupper end of the screw shaft 43 and works in a cylinder 51 secured onthe housing 11. An hydraulic or other pressure fluid is sup plied to thespace in the cylinder 51 above the piston 50 from a suitable source (notshown) and acts downwardly on the piston 59 to relieve a substantialportion of the load from the screw shaft. Thus, the motor 44 can berelatively small for accurate control.

While a particular embodiment of the invention has been described andillustrated, by way-of example, it is to be understood that variouschanges and modifications can be made in the details of constructionwithout departing from the spirit of the invention except as defined inthe appended claims.

What is claimed is:

1. In a four-high rolling mill having working rolls disposed betweenmain backing rolls; first auxiliary backing rolls in front and in backof one of the working rolls and in rolling contact with the latter toprevent bowing out from between the main backing rolls, a laterallyarranged series of second auxiliary backing rolls for rolling contactwith the other of the working rolls, said other working roll beingsupported between the said one working roll, one of said main backingrolls and said second auxiliary backing rolls means individuallysupporting each of said second auxiliary backing rolls for movement intorolling contact with the related working roll, adjustable force meansfor urging said second auxiliary backing rolls against the relatedworking roll with an adjustable force, and a plurality of laterallyspaced means responsive to the variations of thickness of a sheet rolledbetween said working rolls and operatively connected to said adjustableforce means to thereby adjust the pressure between the Working rollsaccording to the variations in the strip and thereby maintaining thethickness of the rolled sheet constant across the sheet, said laterallyspaced means being in longitudinal alignment with each of said secondauxiliary backing rolls.

2. In a rolling mill; the combination of upper and lower Working rollsfor rolling a sheet passed therebe tween, main backing rolls disposedabove and below said s upper and lower working rolls, respectively, theaxes .ot said working rolls being parallel and offset relative to aplane extending through the axes of said main backing rolls, auxiliarybackingmeans associated with at least one 1 for movement of the lattertoward and away from said one working roll, adjustable force meansseparately urging each of said auxiliary backing rolls in thedirectiontoward said one working roll with an adjustable force to resist bowingout of said one working roll from between the related main backing rolland the other of said working rolls, adjustable force, and a pluralityof'lateraily spaced means responsive to the variations of thickness .ofa sheet rolled between said working rolls and operatively connected tosaid adjustable force means to thereby adjust the pressure between theworking rolls according to the variations in the strip and therebymaintaining the thickness of the rolled sheet constant across the sheet,said laterally spaced means being in longitudinal alignment with each ofsaid auxiliary backing rolls.

3. In a rolling mill; the combination of upper and lower Working .rollsfor rolling a sheet passed therebetween, main backing rolls disposedabove and below said upper and lower working rolls, respectively,auxiliary backing rolls in front and in back of one of said workingrolls and in rolling contact with said one working roll to preventbowing of the latter, a series of second auxiliary backing rollsdisposed in 'end-to-end arrangement with their axes parallel to the axisof the other of said Working rolls, said other Working roll beingsupported between the said one working roll, one of said main backingrolls and said second auxiliary backing rolls, means individuallysupporting each of said second auxiliary backing rolls in rollingcontact with said other Working roll, variable contact pressure meansfor urging each of said second auxiliary backing rolls against saidother working roll with a variable contact pressure, and a plurality oflaterally spaced means responsive to the variations of thickness of asheet rolled between said working rolls and operatively connected tosaid variable contact pressure means to thereby-adjust the pressurebetween the working rolls according to the variations in the strip andthereby maintain the thickness of the rolled sheet constant across thesheet, said laterally spaced means being in longitudinal alignment witheach of said second auxiliary backing rolls.

4. In a rolling mill; the combination of upper and lower working rollsfor rolling a sheet passed therebetween, main backing rolls disposedabove and below said upper and lower working rolls, respectively, theaxes of said working rolls being parallel and offset relative to a planeextending through the axes of said main backing rolls, first auxiliarybacking rolls extending parallel to said upper working roll and inrolling contact with the latter at the front and back of said upperworking roll, a series of second auxiliary backing rolls in end-to-endrelationship and arranged parallel to said lower working roll, saidother working roll being supported between the said one working roll,one of said main backing rolls and said second auxiliary backing rolls,means individually supporting each of said second auxiliary backingrolls in rolling contact with said lower working roll at the side of thelatter facing away from said plane through the axes of the main backingrolls, adjustable contact pressure means individually urging each ofsaid second auxiliary backing rolls against the related axial portion ofsaid lower working roll with an adjustable contact pressure,

and a plurality of laterally spaced means responsive to the variationsof thickness of a sheet rolled between said working rolls andoperatively connected to said variable contact pressure means to therebyadjust the pressure between the working rolls according to thevariations in the strip and thereby maintain the thickness of the rolledsheet constant across the sheet, said laterally spaced means being inlongitudinal alignment with each of said second auxiliary backing rolls.

5. In a rolling mill; the combination of upper and lower working rollsfor rolling a sheet passed therebetween, main backing rolls disposedabove and below said upper and lower working rolls, respectively, theaxes of said working rolls being parallel and offset forwardly relativeto a plane extending through the axes of said main backing rolls, aseries of auxiliary backing rolls in end-to-end arrangement in front ofsaid lower working roll and with their axes extending parallel to theaxis of, said lower working roll, the said upper working roll beingsupported between said lower working roll and auxiliary backing rolls inthe direction toward said lower Working roll for rolling contact withthe latter at a variable contact pressure, said auxiliary backing rollsbeing located to be movable rectilinearly in directions substantiallybisecting the angle enclosed by tangents to said lower working roll atthe points of contact of the latter with said upper Working roll andwith said main backing roll below the lower Working roll, and aplurality of laterally spaced means responsive to the variations ofthickness of a sheet rolled between said working rolls and operativelyconnected to said variable contact pressure means to thereby adjust thepressure between the working rolls according to the variations in thestrip and thereby maintain the thickness of the rolled sheet constantacross the sheet, said laterally spaced means being in longitudinalalignment with each of said auxiliary backing rolls.

6. In a rolling mill; the combination of upper and lower working rollsfor rolling a sheet passed therebetween, main backing rolls disposedabove and below said upper and lower working rolls, respectively, aseries of end-to-end arranged auxiliary backing rolls disposed at oneside of one of said working rolls and in rolling contact with thelatter, pressure fluid actuated means for each of said auxiliary workingrolls operative to urge the latter individually against said one Workingroll with an adjustably variable contact pressure force, means forsensing deviations of the actual thicknesses of a sheet rolled betweensaid working rolls from a preselected thickness at laterally spacedlocations corresponding to and aligned with said auxiliary backing rollssaid means producing a signal upon deviation from said preselectedthickness, and control means acting in response to signals from saidsensing means to control said adjustably variable force exerted by saidpressure fluid actuated means in the direction compensating for anydeviations from said preselected thickness to thereby adjust thepressure between the working rolls according to the variations in thestrip and thereby maintain the thickness of the roll sheet constantacross the sheet.

7. In a rolling mill; the combination of upper and lower working rollsfor rolling a sheet passed therebetween, main backing rolls disposedabove and below and in rolling contact with said upper and lower workingrolls, respectively, said working rolls being disposed with the axesthereof ofiset forwardly relative to a plane passed through the axes ofsaid main backing rolls, auxiliary backing rolls arranged in cnd-to-endrelationship and in rolling contact with said lower working roll at thefront of the latter, the said upper working roll being supported betweensaid lower working roll and one of said main backing rolls, meansindividually supporting each of said auxiliary backing rolls formovement toward and away from said lower working roll, pressure fluidmotors connected to each of said auxiliary backing means, a source ofpressure fluid, means for supplying pressure fluid from said source,means for returning pressure fluid to said source, valve means connectedto each of said pressure fluid motors and to said pressure fluidsupplying and returning means, said valve means being operative tocontrol the pressure acting in the related pressure fluid motor; aplurality of laterally spaced control means including gauging meansoperative to produce electrical signals in response to deviations of thethickness of the related portion of the rolled sheet from saidpreselected thickness, at locations corresponding to said auxiliarybacking rolls, and electric valve operating means for each of said valvemeans connected to the related gauging means to control the associatedvalve means in response to the electrical signals emanating from saidgauging means to adjust the pressure between the working rolls accordingto variations in the strip and thereby maintain the thickness of theroll sheet constant across the sheet.

References Cited in the file of this patent UNITED STATES PATENTS1,466,459 Perry Aug. 28, 1923 1,953,165 George Apr. 3, 1934 2,677,978Dahlstrom May 11, 1954 2,685,807 Hudson Aug. 10, 1954

